Apple shifts from AFP file sharing to SMB2 in OS X 10.9 Mavericks

In OS X Mavericks, Apple will begin migrating from its own legacy Apple Filing Protocol to Microsoft's SMB2 in an effort to enhance performance, security and cross platform file sharing.

From Apple Insider:

Apple has maintained and enhanced its own AFP file sharing since it was first introduced in the late 1980s as part of the original Macintosh's easy-to-use AppleTalk networking system (below). The company then transitioned AFP from its own proprietary AppleTalk transport to the Internet's TCP/IP, where it has remained the default protocol for Mac to Mac "personal file sharing" on OS X.

SMB ("Server Message Block") originated at IBM, but was popularized and greatly expanded by Microsoft as the default Windows File Sharing protocol. Like Apple, Microsoft transitioned its SMB file sharing protocol from its original NetBIOS transport to TCP/IP.